Gas-phase CO2Emission toward Cepheus A East: the result of shock activity?
SONNENTRUCKER P., GONZALEZ-ALFONSO E., NEUFELD D.A., BERGIN E.A., MELNICK G.J., FORREST W.J., PIPHER J.L. and WATSON D.M.
Abstract (from CDS):
We report the first detection of gas-phase CO2emission in the star-forming region Cepheus A East, obtained by spectral line mapping of the ν2bending mode at 14.98 µm with the Infrared Spectrograph on board the Spitzer Space Telescope. The gaseous CO2emission covers a region about 35''x25'' in extent and results from radiative pumping by 15 µm continuum photons emanating predominantly from the HW2 protostellar region. The gaseous CO2 exhibits a temperature distribution ranging from 50 to 200 K. A correlation between the gas-phase CO2distribution and that of H2S(2), a tracer of shock activity, indicates that the CO2molecules originate in a cool postshock gas component associated with the outflow powered by HW2. The presence of CO2ice absorption features at 15.20 µm toward this region and the lack of correlation between the IR continuum emission and the CO2gas emission distribution further suggest that the gaseous CO2molecules are mainly sputtered off grain mantles (by the passage of slow nondissociative shocks with velocities of 15-30 km/s) rather than sublimated through grain heating.
ISM: Clouds - ISM: Individual: Name: Cepheus A East - ISM: Jets and Outflows - ISM: Molecules